Models and parametrizations of hadro- and photo- production reactions on nucleons

The non-perturbative regime of QCD is populated by an array of hadronic resonances. Precisdion data on polarization observables with large angular coverage from exisitng and planned e.m. facilities have ushered in a renaissance in reaction theory and light hadron spectroscopy. Baryon resonance production gives a strong contribution to the reaction cross sections in these experiments. But non-resonant contributions to the scattering and reaction observables, particularly in single meson production experiments, generally are not small. This complicates the extraction of the nucleon resonance spectrum from data. We apply a coupled-channel dynamical model and the Chew-Mandelstam parametrization approach to gain a better understanding of the single meson production experiments and what they say about the nucleon resonance spectrum.